Optical material and optical element

Abstract

Provided is an optical element, which is formed by vacuum-sintering a molded body of ceramic particles having an average particle diameter of 1 μm or more and 10 μm or less and including Ln x Al y O [x+y]×1.5 (Ln represents a rare-earth element, x represents 1≦x≦10, and y represents 1≦y≦5). Ln preferably includes at least one kind selected from La, Gd, Yb, and Lu. The optical element preferably has a refractive index of 1.85 or more and 2.06 μm or less, and an Abbe number of 48 or more and 65 or less. The optical element having optical properties of high refractive index and low dispersibility is obtained.

1 . An optical element, comprising a vacuum-sintered body comprising a plurality of ceramic particles,
 wherein the ceramic particles each comprise Ln x Al y O [x+y]×1.5 , where Ln represents a rare-earth element, x represents 1≦x≦10, and y represents 1≦y≦5, and have an average particle diameter of 1 μm or more and 10 μm or less.   
     
     
         2 . The optical element according to  claim 1 , wherein Ln comprises at least one kind selected from La, Gd, Yb, and Lu. 
     
     
         3 . The optical element according to  claim 1 , which has a refractive index of 1.85 or more and 2.06 μm or less, and an Abbe number of 48 or more and 65 or less. 
     
     
         4 . An optical element, comprising a vacuum-sintered body comprising a plurality of particles each having a two-layer structure comprising a ceramic particle and a coating layer, wherein the ceramic particle comprises Ln x Al y O [x+y]×1.5 , where Ln represents a rare-earth element, x represents 1≦x≦10, and y represents 1≦y≦5, and has an average particle diameter of 1 μm or more and 10 μm or less; and the coating layer comprises a ceramic having a lower sintering temperature than a sintering temperature of the ceramic particle. 
     
     
         5 . The optical element according to  claim 4 , wherein the coating layer comprises glass. 
     
     
         6 . The optical element according to  claim 4 , wherein Ln comprises at least one kind selected from Y, La, Gd, Yb, and Lu. 
     
     
         7 . The optical element according to  claim 4 , which has a refractive index of 1.85 or more and 2.06 μm or less, and an Abbe number of 48 or more and 65 or less. 
     
     
         8 . The optical element according to  claim 4 , wherein the particle having a two-layer structure has a spherical shape.